Plastic separating layer

ABSTRACT

Plastic layer that has release properties towards adhesives, where the materials that produce the release properties are incorporated in the plastic layer and can be extruded with it.

DESCRIPTION

[0001] The invention relates to a plastic layer that has releaseproperties towards adhesives and/or adhesive materials.

[0002] Such layers generally consist of silicone and are applied to aplastic film or a similar substrate in a separate operation.

[0003] The purpose of the invention is to provide these releaseproperties earlier, in the course of the production process.

[0004] In the solution to this problem proposed by the invention, thematerials that produce the release properties are incorporated in theplastic layer and can be extruded with it.

[0005] This not only facilitates production very considerably; the levelof the release properties is easy to set as well.

[0006] In accordance with an advantageous further development of theinvention, the basic polymer is provided with modified properties, as aresult of which the release properties are achieved.

[0007] The required strength of the release properties can be takenaccount already in production of the basic polymer.

[0008] In another advantageous further development of the invention, therelease additive incorporated is based on silicone compounds.

[0009] The level of the release properties can be controlled very easilywhen the additive is incorporated in this way too.

[0010] It is also very advantageous if in accordance with anotherfurther development of the invention substances similar to polyolefinsare incorporated as release additives.

[0011] All of these developments make sure that the materials with whichthe release properties are achieved only migrate into the adhesive to aninsignificant extent if at all.

[0012] It has also proved to be very advantageous if the releaseadditives are incorporated in the plastic during polymerisation.

[0013] In another advantageous development, the release additives areembedded firmly in the plastic matrix.

[0014] In a further advantageous development of the invention, fillersthat are, for example, structured as inorganic compounds are provided asrelease additives.

[0015] It has proved to be particularly advantageous in production ofthe plastic layer if the layer is manufactured from a masterbatch.

[0016] In this case, the masterbatch can contain a consistent proportionof the release additives; the final percentage accounted for by therelease material is then determined by the plastic-to-masterbatch mixingratio.

[0017] The plastic layer in accordance with the invention can be used asa single-layer material. This single-layer material can be extruded ontoa substrate layer.

[0018] A plastic film or a paper web can, for example, be provided asthe substrate layer.

[0019] In accordance with another further development of the invention,it is, however, also possible for the layer to be produced by thecoextrusion process. In this case a substrate layer can be provided withthe plastic layer with release properties not only on one side but alsoon both sides.

[0020] In accordance with another advantageous further development ofthe invention, the thickness of the plastic layer is in the 5 mm range.

[0021] The release properties can be influenced even more if inaccordance with another further development of the invention the plasticlayer and/or the substrate film for it is embossed.

[0022] In a preferred embodiment, a plastic film is produced by thecoextrusion process together with a plastic layer with releaseproperties. The opposite side of the plastic film from the plastic layercan be coated with an adhesive and the film can then be wound up, therelease properties of the plastic layer preventing the adhesive fromsticking firmly to this layer. The release properties of the plasticlayer can be reached in different ways. It is, for example, possible forthe basic polymer to be provided with modified properties already. Itis, however, also possible for release additives based on siliconecompounds to be incorporated. Another possibility is for substancessimilar to polyolefins to be incorporated as release additives.

[0023] The release additives can either be incorporated in the plasticduring polymerisation or be embedded firmly in the plastic matrix.

[0024] It is in addition possible to provide fillers that are, forexample, structured as inorganic compounds as release additives.

[0025] It has proved to be advantageous in the production of the releaselayer if this layer is manufactured from a masterbatch. In this case,the masterbatch can contain a consistent proportion of the releasecomponents, while the final percentage is determined by the addition ofplastic.

[0026] The coextrusion process has proved to be particularly effectivein the production operation itself, it being possible to provide therelease layer on either one or both sides.

[0027] It is, however, also possible to apply the release layer to asubstrate web by the extrusion process; a plastic film or a paper webcan be used here as the substrate web.

[0028] The thickness of the plastic layer is chosen according to therequirements in each individual case; a thickness of about 5 μ hasproved to be particularly advantageous.

[0029] The release layer or—if it is applied to a substrate film—thecomplete material combination can in addition be embossed, in order toinfluence the release properties even more.

1. Plastic layer that has release properties towards adhesives, whereinthe materials that produce the release properties are incorporated inthe plastic layer and can be extruded with it.
 2. Plastic layeraccording to claim 1 , wherein the basic polymer is provided withmodified properties, as a result of which the release properties areachieved.
 3. Plastic layer according to claim 1 , wherein the releaseadditive incorporated is based on silicone compounds.
 4. Plastic layeraccording to claim 1 , wherein substances similar to polyolefins areincorporated as release additives.
 5. Plastic layer according to one ofthe previous claims, wherein the release additives are incorporated inthe plastic during polymerisation.
 6. Plastic layer according to one ofclaims 1 to 4 , wherein the release additives are embedded firmly in theplastic matrix.
 7. Plastic layer according to one of the previousclaims, wherein fillers that are, for example, structured as inorganiccompounds are provided as release additives.
 8. Plastic layer accordingto one of the previous claims, wherein the layer is manufactured from amasterbatch.
 9. Plastic layer according to one of the previous claims,wherein the layer is produced by the coextrusion process.
 10. Plasticlayer according to claim 9 , wherein the layer is extruded together witha substrate layer made of plastic.
 11. Plastic layer according to one ofclaims 1 to 8 , wherein the layer is extruded onto a substrate web, forexample a web of paper.
 12. Plastic layer according to one of theprevious claims, wherein the layer is located on either one or bothsides of a substrate layer.
 13. Plastic layer according to one of theprevious claims, wherein the thickness of the layer is in the 5 mmrange.
 14. Plastic layer according to one of the previous claims,wherein the plastic layer with the release properties and/or thesubstrate film for it is embossed.